Have a 2005 5.0 V8 Volvo Penta OSI-E with 180 hours (has Volvo full synthetic 30W). When running, the oil pressure gradually drops from 60 to 25 over an hour or so. If running hard (4000 RPM for extended period of time), eventually get a backfire - easing back seems to fix it but recently when coming off plane the pressure dropped to below 20 and heard valve tapping and engine ran rough - started every 15 minutes after when docked and pressure gradually climbed back.
From the Blackstone report:
The viscosity of this oil measured in the SAE 20W-grade range. Only a trace of gas was in the oil so
it could be that this engine shears an oil's viscosity a little. The universal averages show typical wear for this
type of marine engine after 24 hours of oil use. This oil was in use for 12 hours and all wear metals read
below averages, which is a good indication of normally wearing parts at 180 hours. Silicon and insolubles
were both low, showing normal air and oil filtration. No moisture or coolant was present in this sample.
Looks okay.
Could the lowered viscosity from shear (?) (20W vs 30W which is the weight of the syn oil put in) cause my issue.
Tom
From the Blackstone report:
The viscosity of this oil measured in the SAE 20W-grade range. Only a trace of gas was in the oil so
it could be that this engine shears an oil's viscosity a little. The universal averages show typical wear for this
type of marine engine after 24 hours of oil use. This oil was in use for 12 hours and all wear metals read
below averages, which is a good indication of normally wearing parts at 180 hours. Silicon and insolubles
were both low, showing normal air and oil filtration. No moisture or coolant was present in this sample.
Looks okay.
Could the lowered viscosity from shear (?) (20W vs 30W which is the weight of the syn oil put in) cause my issue.
Tom
